1. Field of the Invention
This invention generally relates to a gateway apparatus mounted on a vehicle and a routing method that relay data between communication networks.
2. Description of the Related Art
In these years, multiple electronic control units (ECUs) are mounted on a vehicle. Referring to FIG. 38, there are provided, for example, an engine ECU, a door control ECU, an air bag ECU, an audio ECU, and a navigation ECU. A gateway apparatus is necessary for routing data so that the ECUs communicate with each other via LANs having different communication protocol and different bit rates. Japanese Patent Application Publication No. 2003-244187 (hereinafter, referred to as Document 1) and Japanese Patent Application Publication No. 2003-264571 (hereinafter, referred to as Document 2) disclose gateway apparatus having a routing function implemented by software.
The gateway apparatus relays data that are sent and received on multiple different network systems, and realizes gateway functions such as a communication protocol conversion and packet filtering. This allows the nodes connected to different network systems to communicate with each other.
The gateway apparatuses disclosed in Document 1 and Document 2, however, have the gateway functions implemented by software. Therefore, as the ECUs are occupied by application other than routing at a high ratio, relay processing is delayed.
In addition, an increased number of channels makes it complicated to search for a channel via which the data is relayed, and needs a longer time for routing. Furthermore, an increased number of frames to be managed needs a longer time to process various information for routing, and increases the waiting time on the gateway apparatus. This degrades throughput. There is another problem that a buffer structure becomes complex so as to suppress frame loss on the gateway apparatus.